running 235-30-20. Yes 225-30-20 would fit better but i decided to go with 235's anyways. Rest assured based on the OE size 235-45-17, the rolling diameter on the 235-30-20 is almost perfect. Also, no rubs so far.

Glad to see you went with a smaller size that what you originally planed. Suits it much better

I don't want to be the one to break it to you but 245/35R20 is a ridiculous size to put on a GS. That is over 5% larger in diameter. First off 245 will crown like hell on a 7.5" rim and with having a 35% sidewall it makes the tire over 1" taller in height and will rub every turn you make and no to mention through your speedometer completely off. The proper size you should be running without having any problems is 225/30R20

So what exactly is sidewall? Is this needed? I am not the best driver in the world and happen to get a lot of curb checks, I am working on being less aggressive now that I have a Lexus and not a truck lol. Will having a higher Sidewall prevent me from dinging any wheels I may get?

So what exactly is sidewall? Is this needed? I am not the best driver in the world and happen to get a lot of curb checks, I am working on being less aggressive now that I have a Lexus and not a truck lol. Will having a higher Sidewall prevent me from dinging any wheels I may get?

I think you need at least 65 series sidewall to clear most curbs. The thicker the sidewall, the thicker the tire. If you are rolling on 20's, you only have about a inch or so sidewall, so this would not help you in anyway.